The present invention relates to screen printing machines in general, and more particularly to improvements in means for applying pressure against that portion of a moving web of fabric or the like which is in contact with the stencil.
It is well known to employ in a screen printing machine a counter-pressure beam which is disposed opposite the stencil and defines with the latter a gap for the passage of a web of the material to be printed and of the customary back cloth. The stencil is a hollow cylinder or an endless band which is trained over several rollers including at least one tensioning roller. A liquid applying device or squegee (e.g., a roll) is mounted in the interior of the stencil to supply a liquid in the region where the stencil contacts the fabric whereby the stencil allows the liquid to come into contact with selected portions of the moving fabric to form thereon a design of predetermined configuration.
A drawback of presently known counter-pressure beams is that they are likely to sag midway between the ends so that the pressure between the stencil and the fabric varies from the marginal portions toward the center of the fabric. This affects the quality of the printing operation; in fact, it can happen that the pressure midway between the ends of the stencil is so low that the liquid cannot contact the median portion of the fabric.